From the past, in an imaging apparatus for diagnosis such as an optical coherent tomography (OCT) apparatus for diagnosis, an optical frequency domain imaging (OFDI) apparatus for diagnosis utilizing wavelength sweep and the like, there has been used, as a probe inserted inside a body cavity such as a blood vessel, an optical probe unit which is installed with a transmitting and receiving unit carrying out optical transmission and reception and an optical fiber (for example, see Japanese unexamined patent publication No. 2000-097845).
In the imaging apparatus for diagnosis, in order to achieve a radial scan inside a body cavity by the transmitting and receiving unit, there is carried out an operation in which while rotating the transmitting and receiving unit in a state of inserting the optical probe unit inside the body cavity, the unit is moved in an distal direction and in an opposite direction thereof (axial direction) inside the body cavity.
In order to realize a radial operation of such a transmitting and receiving unit, a scanner & pull-back unit is usually provided in the imaging apparatus for diagnosis. Then, there are provided, in the scanner & pull-back unit, with a rotational drive unit for rotating the transmitting and receiving unit and the optical fiber installed in the optical probe unit while moving them in the axial direction and with a fixed unit connected optically to a main body control unit of the imaging apparatus for diagnosis, and an optical transmission by a photo coupling unit is carried out between the rotational drive unit and the fixed unit.